Hitachi IR.Station, Hardware Manual

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1 BEFORE USE
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„ Grounding point
Provide Class D* or better independent grounding. Do not use any other existing ground as a
substitute. It is particularly important that the grounding point for the Programmable Controller
be at least 15 m away from an AC panel grounding point.
* Class D grounding is defined in the Technical Standard for Electrical Facilities of Japan. This
standard states that the grounding resistance must be 100 ohms or less for equipment operating
on 300 VAC or less, and 500 ohms or less for devices that shut down automatically within 0.5
seconds when shorting occurs in low tension lines.
It is the best that the grounding wire be welded to the steel frame of a building. In case when
the aforesaid is impossible, bury the grounding rod in earth.
AC panel
PCs panel
LG ground
Keep at least 15 meters between
grounding point of the PCs panel
and the AC panel.
Steel
frames
FG ground
Figure 1-3 Grounding Specifications
„ Noise
Do not install the Programmable Controller inside or near a panel on which a high-voltage device
such as inverter is mounted. Make a shielding plate to protect the CPU or I/O unit main frames
and cables from electromagnetic or electrostatic induction.
„ External circuitry
Partial damage may affect the entire circuitry of the Programmable Controller. Ensure that the
emergency stop circuit incorporated in the Programmable Controller consists of an external relay
circuit.